struct - How to accept as one data type and store in a defined structure using functions in C? -

im having trouble, returning defined structure, function scan_sci suppose take input source string representing positive number in scientific notation, , breaks components storage in scinot_t structure. example input 0.25000e4

  #include <stdio.h>     #include <stdlib.h>     #include <math.h>      typedef struct{         double mantissa;         int exp;     }sci_not_t;      int scan_sci (sci_not_t *c);      int main(void){          sci_not_t inp1, inp2;          printf("enter mantissa in range [0.1, 1.0) exponent: ");         scan_sci(&inp1);         printf("enter second number same specifications above: ");         scan_sci(&inp2);             system("pause");         return 0;     }      int scan_sci (sci_not_t *c){          int status;         double a;         int b;          status = scanf("%lf %d", &c->mantissa, &c->exp);          = c->mantissa;         b = c->exp;         *c = pow(a,b);          if (status == 2 && (c->mantissa >= 0.1 && c->mantissa < 1.0) ){             status = 1;         }else{             printf("you did not enter mantissa in correct range \n");             status = 0;         }           return (status);     }      sci_not_t sum(sci_not_t c1, sci_not_t c2){          return c1 + c2;     }      sci_not_t product(sci_not_t c1, sci_not_t c2){          return c1 * c2;     } 

here's code reads console , puts value in scinot_t there's no validation whatsoever.

it reads entire string using scanf 2 parts. first part %[^e] reads char that's not 'e'. reads 'e' , exponent.

the mantissa read string first , reparsed using sscanf.

#include <stdlib.h>  typedef struct {     double mantissa;     int exp; }scinot_t;  void scan_sci(scinot_t* s);  int main(void){   scinot_t d;    printf("enter value: ");   scan_sci(&d);    printf("mantissa %lf exponent %d\n", d.mantissa, d.exp);   return 0; }  void scan_sci (scinot_t *sn){   char inp1[20];   scanf("%[^e]e%d", inp1, &sn->exp);   sscanf(inp1, "%lf", &sn->mantissa);   return; } 

to test mantissa range update main this:

int main(void){   scinot_t d;    printf("enter value: ");   (;;) {     scan_sci(&d);     if (d.mantissa>=0.1 && d.mantissa<=1.0)       break;     printf("you did not enter mantissa in correct range\nenter value: ");   }    printf("mantissa %lf exponent %d\n", d.mantissa, d.exp);   return 0; }